Magnetic refrigeration system

ABSTRACT

According to one embodiment, a magnetic refrigeration system includes a first heat exchange section, a magnetic field changing section, a first heat transport medium, a second heat transport medium, and a transport section. The first heat exchange section includes a magnetocaloric effect material. The magnetic field changing section is configured to change magnetic field to the first heat exchange section. The second heat transport medium is separated from the first heat transport medium. The second heat transport medium is different from the first heat transport medium in specific heat per unit volume. The transport section is configured to sequentially feed the first heat exchange section with the first heat transport medium and the second heat transport medium.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation application of International Application PCT/JP2010/069297, filed on Oct. 29, 2010; the entire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a magnetic refrigeration system.

BACKGROUND

Recently, as one of the environment-conscious and efficient refrigeration technologies, the magnetic refrigeration technology using the magnetocaloric effect has been raising expectations and activating research and development. In the magnetic refrigeration technology, a magnetic refrigeration cycle is configured using the magnetocaloric effect to produce a high temperature section and a low temperature section.

As one of such magnetic refrigeration technologies, the refrigeration technology called the AMR (active magnetic regenerative refrigeration) technique is proposed. Conventionally, the lattice entropy has been placed as an impediment to magnetic refrigeration in the cryogenic region. However, the AMR technique rather actively utilizes the lattice entropy. In the AMR technique, the magnetic refrigeration operation using the magnetocaloric effect is performed by a component including a magnetocaloric effect material. Simultaneously, the cold heat generated by this magnetic refrigeration operation is stored in that component.

The AMR technique can achieve a higher heat exchange efficiency than the gas refrigeration technology using the gas compression-expansion cycle.

However, from the viewpoint of energy saving and the like, further improvement in heat exchange efficiency is desired.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view for illustrating a magnetic refrigeration system according to a first embodiment;

FIG. 2 is a schematic sectional view for illustrating the heat exchange section;

FIG. 3 is a flow chart for illustrating the function of the heat exchange section according to the first embodiment;

FIGS. 4A and 4B are schematic sectional views for illustrating heat exchange in the heat exchange section according to the first embodiment;

FIG. 5 is a schematic view for illustrating a magnetic refrigeration system according to a second embodiment;

FIGS. 6A and 6B are schematic views for illustrating magnetic refrigeration systems according to a third embodiment;

FIGS. 7A and 7B are schematic sectional views for illustrating the heat exchange section 1 of the magnetic refrigeration system according to the embodiment;

FIG. 8 is a schematic sectional view for illustrating a heat exchange section 51 of the AMR magnetic refrigeration system according to the comparative example; and

FIG. 9 is a graph showing the comparison between the heat transport efficiency in Practical example 1 and the heat transport efficiency in Comparative example 1.

DETAILED DESCRIPTION

In general, according to one embodiment, a magnetic refrigeration system includes a first heat exchange section, a magnetic field changing section, a first heat transport medium, a second heat transport medium, and a transport section.

The first heat exchange section includes a magnetocaloric effect material.

The magnetic field changing section is configured to change magnetic field to the first heat exchange section.

The second heat transport medium is separated from the first heat transport medium.

The second heat transport medium is different from the first heat transport medium in specific heat per unit volume.

The transport section is configured to sequentially feed the first heat exchange section with the first heat transport medium and the second heat transport medium.

Embodiments will now be illustrated with reference to the drawings. In the drawings, similar components are labeled with like reference numerals, and the detailed description thereof is omitted appropriately.

First Embodiment

FIG. 1 is a schematic view for illustrating a magnetic refrigeration system according to a first embodiment.

As shown in FIG. 1, the magnetic refrigeration system 100 includes a heat exchange section (ARM bed) 1 (first heat exchange section), a magnetic field generating section 2, a moving section 3, a high temperature side heat exchange section 4 (second heat exchange section), a low temperature side heat exchange section 5 (second heat exchange section), a piping 6, a piping 7, a heat transport medium 8, a heat transport medium 9, a transport section 10, a transport section 11, and a control section 24.

FIG. 2 is a schematic sectional view for illustrating the heat exchange section.

In FIG. 2, the moving direction of the heat transport medium 8, 9 is taken as x direction, and a direction perpendicular thereto is taken as y direction.

The heat exchange section 1 including a magnetocaloric effect material includes a region 14, a region 12 (first region) connected to the piping 6, and a region 13 (second region) connected to the piping 7.

The region 14 is configured to include a magnetocaloric effect material. The region 14 can be configured to include a magnetocaloric effect material such as Gd (gadolinium).

The region 12 is provided so as to penetrate through the region 14. Thus, the outer peripheral surface of the region 12 is in contact with the region 14. The region 12 can be e.g. a channel penetrating through the region 14.

The heat transport medium 8 fed through the piping 6 is enabled to flow through the region 12.

The region 13 is provided so as to penetrate through the region 14. Thus, the outer peripheral surface of the region 13 is in contact with the region 14. The region 13 can be e.g. a channel penetrating through the region 14.

The heat transport medium 9 fed through the piping 7 is enabled to flow through the region 13.

Here, the heat transport medium 8 flowing through the region 12 and the heat transport medium 9 flowing through the region 13 are separated from each other by the region 14. This prevents the heat transport medium 8 and the heat transport medium 9 from mixing with each other.

As described later, heat generation and heat absorption occur in the region 14. Heat exchange occurs between the region 14 and the heat transport medium 8 located in the region 12. Furthermore, heat exchange occurs between the region 14 and the heat transport medium 9 located in the region 13.

Here, for instance, in the case where the region 12 is fed with a heat transport medium 80 a, the region 13 is fed with a heat transport medium 90 b. In the case where the region 12 is fed with a heat transport medium 80 b, the region 13 is fed with a heat transport medium 90 a.

The aforementioned region 14 preferably has a configuration (e.g., a plate-like body free from voids and the like) for passing the heat transport medium 8, 9 and preventing the heat transport media from mixing with each other. However, the embodiment is not limited thereto.

For instance, a partition, not shown, for preventing passage of the heat transport medium can be provided between the region 14 and the region 12 and between the region 14 and the region 13. For instance, a tubular body can be provided as the partition, not shown, so that the inside of the tubular body constitutes the region 12, 13 and the outside of the tubular body constitutes the region 14. Then, the region 14 can be formed from a sintered body including voids, or formed by packing granular bodies.

The magnetocaloric effect material is not limited to Gd (gadolinium) described above, but only need to be a material developing the magnetocaloric effect. The magnetocaloric effect material can be any of e.g. Gd compounds of Gd (gadolinium) mixed with various elements, intermetallic compounds made of various rare earth elements and transition metal elements, Ni₂MnGa alloys, GdGeSi compounds, LaFe₁₃-based compounds, and various magnetic materials such as LaFe₁₃H.

The magnetic field generating section 2 is placed outside the heat exchange section 1 and applies a magnetic field to the heat exchange section 1.

The magnetic field generating section 2 can be e.g. a permanent magnet. The permanent magnet can be e.g. a NdFeB (neodymium-iron-boron) magnet, SmCo (samarium-cobalt) magnet, or ferrite magnet.

The moving section 3 is connected to the magnetic field generating section 2 and changes the relative position of the heat exchange section 1 and the magnetic field generating section 2.

Here, changing the relative position means changing the relative position of the heat exchange section 1 and the magnetic field generating section 2 to enable switching between the position 22 (ON position) where the magnetic field generating section 2 applies the magnetic field to the heat exchange section 1 and the position 23 (OFF position) where the magnetic field generating section 2 does not apply the magnetic field to the heat exchange section 1.

Thus, by causing the moving section 3 to change the relative position of the heat exchange section 1 and the magnetic field generating section 2, the magnetic field can be applied to the heat exchange section 1, and the magnetic field applied to the heat exchange section 1 can be removed. In the heat exchange section 1, heat generation and heat absorption occur by application of the magnetic field and removal of the magnetic field. The details on the function of the heat exchange section 1 will be described later.

The moving section 3 can be e.g. a section for applying mechanical variation to the magnetic field generating section 2 to change the relative position of the heat exchange section 1 and the magnetic field generating section 2.

In the case illustrated in FIG. 1, the magnetic field generating section 2 and the moving section 3 constitute a magnetic field changing section for changing the magnetic field to the heat exchange section 1.

In the case illustrated in FIG. 1, the moving section 3 is connected to the magnetic field generating section 2 to apply mechanical variation to the magnetic field generating section 2. However, alternatively, the moving section 3 may be connected to the heat exchange section 1 to apply mechanical variation to the heat exchange section 1.

The moving section 3 can include e.g. driving means such as a motor.

In the foregoing, as the magnetic field generating section 2, a permanent magnet is illustrated. However, for instance, an electromagnet can also be used as the magnetic field generating section 2. In the case of using an electromagnet as the magnetic field generating section 2, the moving section 3 can be configured to apply mechanical variation to the magnetic field generating section 2. However, alternatively, the moving section 3 can also be configured as e.g. a switch for switching between energization and deenergization of the electromagnet.

The high temperature side heat exchange section 4 performs heat exchange between the heat transport medium 8 heated in the heat exchange section 1 and a heat exchange target, not shown. The high temperature side heat exchange section 4 can be e.g. a section for heating air by performing heat exchange between the heat transport medium 8 at high temperature and air.

The low temperature side heat exchange section 5 performs heat exchange between the heat transport medium 9 subjected to heat absorption in the heat exchange section 1 and a heat exchange target, not shown. The low temperature side heat exchange section 5 can be e.g. a section for cooling air by performing heat exchange between the heat transport medium 9 at low temperature and air.

The piping 6 connects the heat exchange section 1, the high temperature side heat exchange section 4, and the transport section 10 in a closed loop. Thus, the heat transport medium 8 can be circulated in the closed loop channel formed from the heat exchange section 1, the high temperature side heat exchange section 4, the transport section 10, and the piping 6.

The piping 7 connects the heat exchange section 1, the low temperature side heat exchange section 5, and the transport section 11 in a closed loop. Thus, the heat transport medium 9 can be circulated in the closed loop channel formed from the heat exchange section 1, the low temperature side heat exchange section 5, the transport section 11, and the piping 7.

The heat transport medium 8 can be composed of two or more heat transport media different in specific heat per unit volume. The heat transport medium 8 is composed of e.g. a heat transport medium 80 a (first heat transport medium) and a heat transport medium 80 b (second heat transport medium) having a lower specific heat per unit volume than the heat transport medium 80 a.

The heat transport medium 9 can be composed of two or more heat transport media different in specific heat per unit volume. The heat transport medium 9 is composed of e.g. a heat transport medium 90 a (first heat transport medium) and a heat transport medium 90 b (second heat transport medium) having a lower specific heat per unit volume than the heat transport medium 90 a.

The heat transport medium 80 a and the heat transport medium 80 b are separated from each other. The heat transport medium 90 a and the heat transport medium 90 b are separated from each other.

Here, being separated means that heat transport media different in specific heat per unit volume form respective phases with respect to the moving direction of the heat transport media.

In forming phases, it is preferable that each heat transport medium be not mixed with a different heat transport medium. However, the case where a particular heat transport medium is mixed with a different heat transport medium in a volume ratio of 30% or less may also be regarded as forming respective phases.

For instance, the heat transport media can be water and air, which has a lower specific heat per unit volume than water. In this case, air may partially dissolve in water. However, the solubility of air in water is 0 vol % or more and 30 vol % or less. Thus, air and water can form respective phases. That is, it can be regarded that the water phase and the air phase are separated.

The heat transport medium may be any of gas, liquid, and solid. Heat transport media different in specific heat per unit volume can be appropriately selected for use.

In this case, it is preferable to use a combination with a large difference in specific heat per unit volume. For instance, combinations such as gas-liquid, solid-liquid, and solid-gas can be used.

A heat transport medium of gas can be e.g. air or nitrogen gas. A heat transport medium of gas can reduce pressure loss during transportation. A heat transport medium of liquid can be e.g. water, an oil-based medium such as mineral oil and silicone, or a solvent-based medium such as alcohols (e.g., ethylene glycol).

In this case, water has the highest specific heat and is inexpensive. However, water may freeze in the temperature region of 0° C. or less. Thus, it is preferable to use e.g. an oil-based medium, a solvent-based medium, a mixed liquid of water and an oil-based medium, or a mixed liquid of water and a solvent-based medium. Depending on the operating temperature region of the magnetic refrigeration system 100, the liquid can be appropriately changed in kind and mixing ratio.

A heat transport medium of solid can be e.g. resin, metal, or inorganic material such as ceramic.

In this case, for instance, the heat transport medium of solid can be integrally configured, or a granular solid aggregate can be used as the heat transport medium. However, the integrally configured heat transport medium of solid can suppress mixing with a different heat transport medium.

The heat transport medium 8 and the heat transport medium 9 can have either the same configuration or different configurations.

The transport section 10 circulates the heat transport medium 8 in the closed loop channel formed from the heat exchange section 1, the high temperature side heat exchange section 4, the transport section 10, and the piping 6. More specifically, the heat transport medium 80 a and the heat transport medium 80 b are sequentially fed into the heat exchange section 1. The heat transport medium 80 a and the heat transport medium 80 b heated in the heat exchange section 1 are sent to the high temperature side heat exchange section 4. The heat transport medium 80 a and the heat transport medium 80 b heat-exchanged with the heat exchange target, not shown, in the high temperature side heat exchange section 4 are sent again to the heat exchange section 1.

The transport section 11 circulates the heat transport medium 9 in the closed loop channel formed from the heat exchange section 1, the low temperature side heat exchange section 5, the transport section 11, and the piping 7. More specifically, the heat transport medium 90 a and the heat transport medium 90 b are sequentially fed into the heat exchange section 1. The heat transport medium 90 a and the heat transport medium 90 b subjected to heat absorption in the heat exchange section 1 are sent to the low temperature side heat exchange section 5. The heat transport medium 90 a and the heat transport medium 90 b heat-exchanged with the heat exchange target, not shown, in the low temperature side heat exchange section 5 are sent again to the heat exchange section 1.

The transport section 10, 11 can be e.g. any of various pumps.

The control section 24 controls the operation of the moving section 3, the transport section 10, and the transport section 11.

More specifically, when the heat exchange section 1 is fed with the heat transport medium 80 a and the heat transport medium 90 b, the control section 24 controls the operation of the moving section 3, the transport section 10, and the transport section 11 so as to apply a magnetic field to the heat exchange section 1. When the heat exchange section 1 is fed with the heat transport medium 80 b and the heat transport medium 90 a, the control section 24 controls the operation of the moving section 3, the transport section 10, and the transport section 11 so as to remove the magnetic field applied to the heat exchange section 1.

For instance, in performing heat generation, the transport section 10 is controlled to feed the heat exchange section 1 with the heat transport medium 80 a having a higher specific heat per unit volume than the heat transport medium 80 b. Furthermore, the moving section 3 constituting the magnetic field changing section is controlled to apply a magnetic field to the heat exchange section 1.

For instance, in performing heat absorption, the transport section 11 is controlled to feed the heat exchange section 1 with the heat transport medium 90 a having a higher specific heat per unit volume than the heat transport medium 90 b. Furthermore, the moving section 3 constituting the magnetic field changing section is controlled to remove the magnetic field from the heat exchange section 1.

The relationship between application of the magnetic field and removal of the magnetic field in the heat exchange section 1 and the heat transport media different in specific heat per unit volume will be described later.

Next, the function of the magnetic refrigeration system 100 is illustrated.

FIG. 3 is a flow chart for illustrating the function of the heat exchange section according to the first embodiment.

FIGS. 4A and 4B are schematic sectional views for illustrating heat exchange in the heat exchange section according to the first embodiment. More specifically, FIG. 4A shows the case of applying a magnetic field to the heat exchange section 1. FIG. 4B shows the case of removing the magnetic field applied to the heat exchange section.

First, as shown in FIG. 3, the heat exchange section 1 is fed with the heat transport medium 80 a and the heat transport medium 90 b (step S1).

More specifically, the control section 24 controls the transport section 10 to feed the heat transport medium 80 a into the region 12 of the heat exchange section 1. Furthermore, the control section 24 controls the transport section 11 to feed the heat transport medium 90 b into the region 13 of the heat exchange section 1.

Next, the control section 24 controls the moving section 3 to move the magnetic field generating section 2 to the position 22 (ON position) for applying a magnetic field to the heat exchange section 1 (step S2).

The state at this time is as illustrated in FIG. 4A.

When the magnetic field is applied to the heat exchange section 1, the magnetocaloric effect material forming the region 14 generates heat. Thus, the generated heat is absorbed by the transport medium 80 a fed into the region 12 and the transport medium 90 b fed into the region 13.

Next, the control section 24 controls the transport section 10 to feed the heat transport medium 80 b into the region 12 of the heat exchange section 1. Furthermore, the control section 24 controls the transport section 11 to feed the heat transport medium 90 a into the region 13 of the heat exchange section 1 (step S3).

Thus, the transport medium 80 a is ejected from the region 12 toward the high temperature side heat exchange section 4. The transport medium 90 b is ejected from the region 13 toward the low temperature side heat exchange section 5.

Next, the control section 24 controls the moving section 3 to move the magnetic field generating section 2 to the position 23 (OFF position) for not applying a magnetic field to the heat exchange section 1 (step S4).

The state at this time is as illustrated in FIG. 4B.

When the magnetic field applied to the heat exchange section 1 is removed, the magnetocaloric effect material forming the region 14 absorbs heat. Thus, heat is drawn from the heat transport medium 80 b fed into the region 12 and the heat transport medium 90 a fed into the region 13.

After step S4, control returns to step S1.

More specifically, the control section 24 controls the transport section 10 to feed the heat transport medium 80 a into the region 12 of the heat exchange section 1. Furthermore, the control section 24 controls the transport section 11 to feed the heat transport medium 90 b into the region 13 of the heat exchange section 1.

Thus, the transport medium 80 b is ejected from the region 12 toward the high temperature side heat exchange section 4. The transport medium 90 a is ejected from the region 13 toward the low temperature side heat exchange section 5.

By repeating the foregoing procedure, the heat transport medium 8 (heat transport media 80 a, 80 b) is sent to the high temperature side heat exchange section 4. The heat transport medium 9 (heat transport media 90 a, 90 b) is sent to the low temperature side heat exchange section 5.

Then, for instance, heat taken out of the heat transport medium 8 in the high temperature side heat exchange section 4 can be used for air heating. Furthermore, for instance, heat can be absorbed by the heat transport medium 9 in the low temperature side heat exchange section 5 for air cooling.

Here, heat generation of the magnetocaloric effect material by application of a magnetic field and heat absorption of the magnetocaloric effect material by removal of the applied magnetic field are known phenomena, and thus the description thereof is omitted.

Next, feeding the regions 12, 13 of the heat exchange section 1 with heat transport media different in specific heat per unit volume is further described.

By application of a magnetic field, heat is generated by the magnetocaloric effect material and absorbed by heat transport media different in specific heat per unit volume. In this case, even under the same temperature environment, more heat is absorbed by the heat transport medium having a higher specific heat per unit volume.

By removal of the applied magnetic field, heat is absorbed by the magnetocaloric effect material to draw heat from heat transport media different in specific heat per unit volume. In this case, even under the same temperature environment, more heat is drawn from the heat transport medium having a higher specific heat per unit volume.

Here, in step S2, the magnetocaloric effect material generates heat. In this step, the heat transport medium 80 a having a high specific heat per unit volume is fed into the region 12 of the heat exchange section 1, and the heat transport medium 90 b having a low specific heat per unit volume is fed into the region 13 of the heat exchange section 1.

Thus, more heat from the magnetocaloric effect material is absorbed by the heat transport medium 80 a having a higher specific heat per unit volume. That is, heat is selectively provided to the heat transport medium 80 a.

On the other hand, in step S4, the magnetocaloric effect material absorbs heat. In this step, the heat transport medium 80 b having a low specific heat per unit volume is fed into the region 12 of the heat exchange section 1, and the heat transport medium 90 a having a high specific heat per unit volume is fed into the region 13 of the heat exchange section 1.

Thus, a larger amount of heat is drawn from the heat transport medium 90 b having a higher specific heat per unit volume. That is, heat is selectively drawn from the heat transport medium 90 b.

Here, in the heat transport medium 8, in step S2 in which the magnetocaloric effect material generates heat, the heat transport medium 80 a having a high specific heat per unit volume is fed into the region 12 of the heat exchange section 1. In step S4 in which the magnetocaloric effect material absorbs heat, the heat transport medium 80 b having a low specific heat per unit volume is fed into the region 12 of the heat exchange section 1.

Thus, when the magnetocaloric effect material generates heat, the amount of heat is selectively provided to the heat transport medium 80 a. On the other hand, when the magnetocaloric effect material absorbs heat, the amount of heat drawn from the heat transport medium 80 b can be suppressed. As a result, the generated warm heat can be efficiently sent to the high temperature side heat exchange section 4.

In the heat transport medium 9, in step S4 in which the magnetocaloric effect material absorbs heat, the heat transport medium 90 a having a high specific heat per unit volume is fed into the region 13 of the heat exchange section 1. In step S2 in which the magnetocaloric effect material generates heat, the heat transport medium 90 b having a low specific heat per unit volume is fed into the region 13 of the heat exchange section 1.

Thus, when the magnetocaloric effect material absorbs heat, the amount of heat is selectively drawn from the heat transport medium 90 a. When the magnetocaloric effect material generates heat, the amount of heat absorbed from the heat transport medium 90 b can be suppressed. As a result, the generated cool heat can be efficiently sent to the low temperature side heat exchange section 5.

Second Embodiment

FIG. 5 is a schematic view for illustrating a magnetic refrigeration system according to a second embodiment.

As shown in FIG. 5, the magnetic refrigeration system 101 includes a heat exchange section 1, a magnetic field generating section 2, a moving section 3, a high temperature side heat exchange section 4, a low temperature side heat exchange section 5, a piping 6, a piping 7, a heat transport medium 8, a heat transport medium 9, a transport section 10, a transport section 11, a high temperature side ejecting section 16, a low temperature side ejecting section 17, a feeding section 18, and a control section 34.

As in the magnetic refrigeration system 100 described above, the high temperature side heat exchange section 4 performs heat exchange between the heat transport medium 8 heated in the heat exchange section 1 and a heat exchange target, not shown. The low temperature side heat exchange section 5 performs heat exchange between the heat transport medium 9 subjected to heat absorption in the heat exchange section 1 and a heat exchange target, not shown.

In this case, if the heat transport media 8, 9 stagnate inside the high temperature side heat exchange section 4 and the low temperature side heat exchange section 5, the heat exchange efficiency may decrease.

In the following description, as an example, it is assumed that the heat transport medium 80 a, 90 a is liquid (e.g., water) and the heat transport medium 80 b, 90 b is gas (e.g., air).

For instance, the heat transport medium 80 b, 90 b being a gas may stagnate inside the high temperature side heat exchange section 4 and the low temperature side heat exchange section 5. This hampers the inflow of the heat transport medium 80 a, 90 a and may decrease the heat exchange efficiency in the high temperature side heat exchange section 4 and the low temperature side heat exchange section 5. Furthermore, if the temperature of the heat transport medium 80 a is increased by heating, part of the heat transport medium 80 a being a liquid is evaporated. Then, the evaporated gas may coexist (suspend) in the heat transport medium 80 a. In such cases, the phases of the heat transport medium 80 a and the heat transport medium 80 b may be mixed. Furthermore, the heat exchange efficiency in the high temperature side heat exchange section 4 may decrease.

Thus, in this embodiment, a high temperature side ejecting section 16 and a low temperature side ejecting section 17 are provided so that the gas having low contribution to heat exchange is ejected into the atmosphere before flowing into the high temperature side heat exchange section 4 and the low temperature side heat exchange section 5.

More specifically, on the inflow side (upstream side) of the high temperature side heat exchange section 4, a high temperature side ejecting section 16 for ejecting the heat transport medium 80 b is provided. On the inflow side (upstream side) of the low temperature side heat exchange section 5, a low temperature side ejecting section 17 for ejecting the heat transport medium 90 b is provided.

The high temperature side ejecting section 16 and the low temperature side ejecting section 17 can be e.g. a gas-liquid separator including a gas-liquid separation membrane.

By providing a high temperature side ejecting section 16 and a low temperature side ejecting section 17, the above problem can be solved.

The high temperature side ejecting section 16 and the low temperature side ejecting section 17 illustrated in FIG. 5 are provided separately from the high temperature side heat exchange section 4 and the low temperature side heat exchange section 5. However, the embodiment is not limited thereto. For instance, the high temperature side ejecting section 16 may be provided inside the high temperature side heat exchange section 4. The low temperature side ejecting section 17 may be provided inside the low temperature side heat exchange section 5.

Furthermore, the heat transport medium 90 a has a low risk of coexistence of evaporated gas. Thus, the low temperature side ejecting section 17 may be omitted to provide only the high temperature side ejecting section 16.

The feeding section 18 reconfigures the heat transport media 8, 9.

For instance, the feeding section 18 allows the heat transport medium 80 b ejected by the high temperature side ejecting section 16 to be formed again on the outflow side (downstream side) of the high temperature side heat exchange section 4. Furthermore, the feeding section 18 allows the heat transport medium 90 b ejected by the low temperature side ejecting section 17 to be formed again on the outflow side (downstream side) of the low temperature side heat exchange section 5.

In the case described above, after the heat transport medium 80 a passes through the high temperature side heat exchange section 4, the feeding section 18 feeds a prescribed amount of heat transport medium 80 b into the piping 6 to reconfigure the heat transport medium 8 composed of the heat transport medium 80 a and the heat transport medium 80 b. After the heat transport medium 90 a passes through the low temperature side heat exchange section 5, the feeding section 18 feeds a prescribed amount of heat transport medium 90 b into the piping 7 to reconfigure the heat transport medium 9 composed of the heat transport medium 90 a and the heat transport medium 90 b.

More specifically, the feeding section 18 feeds the heat transport medium 80 b in the same amount as the heat transport medium 80 b ejected by the high temperature side ejecting section 16. The feeding section 18 feeds the heat transport medium 90 b in the same amount as the heat transport medium 90 b ejected by the low temperature side ejecting section 17.

The control section 34 controls the operation of the moving section 3, the transport section 10, the transport section 11, and the feeding section 18.

More specifically, when the heat exchange section 1 is fed with the heat transport medium 80 a and the heat transport medium 90 b, the control section 34 controls the operation of the moving section 3, the transport section 10, and the transport section 11 so as to apply a magnetic field to the heat exchange section 1. When the heat exchange section 1 is fed with the heat transport medium 80 b and the heat transport medium 90 a, the control section 34 controls the operation of the moving section 3, the transport section 10, and the transport section 11 so as to remove the magnetic field applied to the heat exchange section 1. Furthermore, the control section 34 controls the operation of the feeding section 18 so as to reconfigure the heat transport media 8, 9.

Next, the function of the magnetic refrigeration system 101 is illustrated.

The function of the heat exchange section 1 can be made similar to that illustrated in FIG. 3.

More specifically, when a magnetic field is applied to the heat exchange section 1 to cause heat generation, the region 12 is fed with the heat transport medium 80 a having a high specific heat per unit volume, and the region 13 is fed with the heat transport medium 90 b having a low specific heat per unit volume.

As described above, the heat transport medium 90 b has a lower specific heat per unit volume. Thus, under the same temperature environment, a larger amount of heat generated is absorbed into the heat transport medium 80 a having a higher specific heat per unit volume. Accordingly, the amount of heat due to heat generation is selectively absorbed into the heat transport medium 80 a. Thus, the heat transport medium 80 a is efficiently heated.

On the other hand, when the magnetic field applied to the heat exchange section 1 is removed to cause heat absorption, the region 12 is fed with the heat transport medium 80 b having a low specific heat per unit volume, and the region 13 is fed with the heat transport medium 90 a having a high specific heat per unit volume.

As described above, the heat transport medium 80 b has a lower specific heat per unit volume. Thus, under the same temperature environment, a larger amount of heat is drawn to the magnetocaloric effect material from the heat transport medium 90 a having a higher specific heat per unit volume. Accordingly, heat is selectively drawn to the magnetocaloric effect material from the heat transport medium 90 a. Thus, the heat transport medium 90 a is efficiently cooled.

Then, the heat transport medium 8 (heat transport media 80 a, 80 b) is sent to the high temperature side heat exchange section 4. The heat transport medium 9 (heat transport media 90 a, 90 b) is sent to the low temperature side heat exchange section 5.

In this case, by the high temperature side ejecting section 16, the heat transport medium 80 b is removed before flowing into the high temperature side heat exchange section 4. By the low temperature side ejecting section 17, the heat transport medium 90 b is removed before flowing into the low temperature side heat exchange section 5.

In the high temperature side heat exchange section 4, for instance, heat taken out of the heat transport medium 80 a can be used for air heating. In the low temperature side heat exchange section 5, for instance, heat can be absorbed by the heat transport medium 90 a for air cooling.

Furthermore, the feeding section 18 reconfigures the heat transport medium 8 on the outflow side (downstream side) of the high temperature side heat exchange section 4. The feeding section 18 reconfigures the heat transport medium 9 on the outflow side (downstream side) of the low temperature side heat exchange section 5.

Third Embodiment

FIGS. 6A and 6B are schematic views for illustrating magnetic refrigeration systems according to a third embodiment. More specifically, FIG. 6A is a schematic view for illustrating a magnetic refrigeration system 100 a using only heat generation of the magnetocaloric effect material. FIG. 6B is a schematic view for illustrating a magnetic refrigeration system 100 b using only heat absorption of the magnetocaloric effect material.

As shown in FIG. 6A, the magnetic refrigeration system 100 a includes a heat exchange section 1, a magnetic field generating section 2, a moving section 3, a high temperature side heat exchange section 4, a piping 6, a heat transport medium 8, a transport section 10, and a control section 24 a.

The control section 24 a controls the operation of the moving section 3 and the transport section 10.

More specifically, when the heat exchange section 1 is fed with the heat transport medium 80 a, the control section 24 a controls the operation of the moving section 3 and the transport section 10 so as to apply a magnetic field to the heat exchange section 1. When the heat exchange section 1 is fed with the heat transport medium 80 b, the control section 24 a controls the operation of the moving section 3 and the transport section 10 so as to remove the magnetic field applied to the heat exchange section 1

Thus, when the magnetocaloric effect material generates heat, heat can be efficiently absorbed by the heat transport medium 80 a having a high specific heat per unit volume. When the magnetocaloric effect material absorbs heat, heat drawn to the magnetocaloric effect material by the heat transport medium 80 b having a low specific heat per unit volume can be suppressed. As a result, the heat exchange efficiency can be improved.

As shown in FIG. 6B, the magnetic refrigeration system 100 b includes a heat exchange section 1, a magnetic field generating section 2, a moving section 3, a low temperature side heat exchange section 5, a piping 7, a heat transport medium 9, a transport section 11, and a control section 24 b.

The control section 24 b controls the operation of the moving section 3 and the transport section 11.

More specifically, when the heat exchange section 1 is fed with the heat transport medium 90 b, the control section 24 b controls the operation of the moving section 3 and the transport section 11 so as to apply a magnetic field to the heat exchange section 1. When the heat exchange section 1 is fed with the heat transport medium 90 a, the control section 24 b controls the operation of the moving section 3 and the transport section 11 so as to remove the magnetic field applied to the heat exchange section 1.

Thus, when the magnetocaloric effect material generates heat, heat absorbed by the heat transport medium 90 b having a low specific heat per unit volume is suppressed. When the magnetocaloric effect material absorbs heat, heat is efficiently drawn to the magnetocaloric effect material by the heat transport medium 90 a having a high specific heat per unit volume. As a result, the heat exchange efficiency can be improved.

Here, the magnetic refrigeration system 100 a can also include a high temperature side ejecting section 16 and a feeding section 18 illustrated in FIG. 5. The magnetic refrigeration system 100 b can also include a low temperature side ejecting section 17 and a feeding section 18 illustrated in FIG. 5.

In the embodiments illustrated above, respective phases of heat transport media different in specific heat per unit volume are formed. The phases of heat transport media thus formed are sequentially fed into the heat exchange section 1. However, the embodiments are not limited thereto.

For instance, by using a switching valve and the like, the heat transport medium fed into the heat exchange section 1 may be switched so that heat transport media different in specific heat per unit volume are sequentially fed into the heat exchange section 1.

That is, it is only necessary that heat transport media different in specific heat per unit volume be sequentially fed into the heat exchange section 1.

Practical Example

Next, a comparison with an AMR magnetic refrigeration system according to a comparative example is described. The comparison is intended to investigate the effect of the magnetic refrigeration system according to the embodiment.

Practical Example 1

FIGS. 7A and 7B are schematic sectional views for illustrating the heat exchange section 1 of the magnetic refrigeration system according to the embodiment. More specifically, FIG. 7A shows the case of applying a magnetic field. FIG. 7B shows the case of removing the applied magnetic field.

The region 14 of the heat exchange section 1 illustrated in FIGS. 7A and 7B is formed from a Gd (gadolinium) plate. The weight of the Gd plate was set to 100 g, the z-direction thickness was set to 3 mm, and the x-direction length was set to 115 mm. As the region 12 and the region 13, linear channels each having a z-direction depth of 3 mm, a y-direction width of 2 mm, and an x-direction length of 115 mm were formed on the Gd plate. In the region 12 and the piping 6 and in the region 13 and the piping 7, a water phase and an air phase were alternately formed. Furthermore, the water phase and the air phase were made equal in volume ratio. The occupied volume per phase was made equal to the channel volume.

First, as shown in FIG. 7A, the water phase was placed in the region 12, and the air phase was placed in the region 13. Then, by applying a magnetic field to the heat exchange section 1, the magnetocaloric effect material (Gd (gadolinium)) was caused to generate heat.

Next, as shown in FIG. 7B, the water phase was ejected from the region 12 so that an air phase was placed in the region 12. Furthermore, the air phase was ejected from the region 13 so that a water phase was placed in the region 13. Then, by removing the magnetic field applied to the heat exchange section 1, the magnetocaloric effect material is caused to absorb heat.

The foregoing process was taken as one cycle. During one cycle, the temperature T_(H) of air and water flowing through the region 12 was measured by a thermocouple in contact with the air and water in the region 12. From the temperature change, the weight of the water phase, and the weight of the air phase in this measurement, the amount of heat absorption was determined, and the heat transport efficiency was calculated.

In this case, the heat transport efficiency was defined by equation (1).

Heat transport efficiency=(Amount of heat absorption of water+Amount of heat absorption of air in region 12)/Theoretical amount of heat generation from Gd (gadolinium) 100 g during magnetic field application of one cycle  (1)

Here, the amount of heat absorption of water is given by specific heat of water (4.2 kJ/kg/K)×density of water (1000 kg/m³)×volume of region 12 (m³)×maximum temperature increase of water (ΔT_(H2O)). The amount of heat absorption of air is given by specific heat of air (1 kJ/kg/K)×density of air (1.29 kg/m³)×volume of region 12 (m³)×temperature increase of air (ΔT_(air)). The theoretical amount of heat generation from Gd 100 g during magnetic field application of one cycle (QGd) was determined by QGd=T (298 K)×magnetic entropy change (ΔS=2.5 kJ/kg/K)×0.1 (kg−Gd).

Comparative Example 1

FIG. 8 is a schematic sectional view for illustrating a heat exchange section 51 of the AMR magnetic refrigeration system according to the comparative example.

First, 100 g of Gd (gadolinium) particles having the magnetocaloric effect with a diameter of 1 mm were packed in a cylindrical container 52 having an inner diameter of 15 mm and a length of 115 mm with a packing ratio of 60%. At the end portion, a partition plate 53 made of a metal mesh was provided. Then, the remaining space inside the heat exchange section 51 was filled with water to produce a heat exchange section 51.

To the heat exchange section 51, a magnetic field having the same intensity as that of Practical example 1 was applied to cause the Gd (gadolinium) particles to generate heat.

Then, the partition plate 53 was moved +1 cm in the X-axis direction to move the water. The moving speed was set to 0.4 cm/s.

Next, the applied magnetic field was removed. After the removal, the partition plate 53 was moved −1 cm in the X-axis direction to move the water. The moving speed was set to 0.4 cm/s.

The foregoing process was taken as one cycle. During one cycle, the temporal change of the temperature of water was measured by a thermocouple placed in the water. From the temperature change and the weight of water, the heat transport efficiency during heat generation was calculated.

In this case, the heat transport efficiency was calculated using the following equation (2).

Heat transport efficiency=Amount of heat absorption of water/Theoretical amount of heat generation from Gd 100 g during magnetic field application of one cycle  (2)

Here, the amount of heat absorption of water is given by specific heat of water (4.2 kJ/kg/K)×density of water (1000 kg/m³)×filling volume of water in cylindrical container 52 (m³)×maximum temperature increase of water (ΔT_(H2O)). The theoretical amount of heat generation from Gd 100 g during magnetic field application of one cycle (QGd) was determined by QGd=T (298 K)×magnetic entropy change (ΔS=2.5 kJ/kg/K)×0.1 (kg−Gd).

FIG. 9 is a graph showing the comparison between the heat transport efficiency in Practical example 1 and the heat transport efficiency in Comparative example 1.

With regard to the temperature measurement, the initial temperature of water and the initial temperature of air were set to 25° C., equal to the ambient temperature.

As shown in FIG. 9, the heat transport efficiency in Practical example 1 was 50%, and the heat transport efficiency in Comparative example 1 was 2.6%. That is, it was confirmed that Practical example 1 achieved a significantly higher heat transport efficiency than Comparative example 1.

The embodiments described above can realize a magnetic refrigeration system capable of improving the heat transport efficiency.

While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions. Moreover, above-mentioned embodiments can be combined mutually and can be carried out.

For instance, the shape, dimension, material, layout and the like of various components in the magnetic refrigeration system 100, the magnetic refrigeration system 101, the magnetic refrigeration system 100 a, the magnetic refrigeration system 100 b and the like are not limited to those illustrated above, but can be appropriately modified. 

What is claimed is:
 1. A magnetic refrigeration system comprising: a first heat exchange section including a magnetocaloric effect material; a magnetic field changing section configured to change magnetic field to the first heat exchange section; a first heat transport medium; a second heat transport medium separated from the first heat transport medium and being different from the first heat transport medium in specific heat per unit volume; and a transport section configured to sequentially feed the first heat exchange section with the first heat transport medium and the second heat transport medium.
 2. The system according to claim 1, wherein the transport section feeds the first heat exchange section with the first heat transport medium having a higher specific heat per unit volume than the second heat transport medium, and the magnetic field changing section applies the magnetic field to the first heat exchange section to cause the heat exchange section to generate heat.
 3. The system according to claim 1, wherein the transport section feeds the first heat exchange section with the first heat transport medium having a higher specific heat per unit volume than the second heat transport medium, and the magnetic field changing section removes the magnetic field applied to the first heat exchange section to cause the heat exchange section to absorb heat.
 4. The system according to claim 1, wherein the first heat exchange section includes a first region and a second region configured to pass the heat transport media, when the first region is fed with the first heat transport medium, the second region is fed with the second heat transport medium, and when the first region is fed with the second heat transport medium, the second region is fed with the first heat transport medium.
 5. The system according to claim 1, wherein one of the first heat transport medium and the second heat transport medium is liquid, and the other is gas.
 6. The system according to claim 1, further comprising: a second heat exchange section configured to perform heat exchange between the first heat transport medium flowing out of the first heat exchange section and a heat exchange target.
 7. The system according to claim 6, further comprising: an ejecting section configured to eject the second heat transport medium to outside on inflow side of the second heat exchange section; and a feeding section configured to feed the second heat transport medium from outside on outflow side of the second heat exchange section.
 8. The system according to claim 7, wherein the first heat transport medium is liquid, the second heat transport medium is gas, and the ejecting section includes a gas-liquid separation membrane.
 9. The system according to claim 7, wherein the feeding section feeds the second heat transport medium in a same amount as the second heat transport medium ejected by the ejecting section.
 10. The system according to claim 1, wherein the magnetocaloric effect material includes at least one selected from the group consisting of Gd (gadolinium), a Gd compound, an intermetallic compound made of various rare earth elements and transition metal elements, a Ni₂MnGa alloy, a GdGeSi compound, a LaFe₁₃-based compound, and LaFe₁₃H.
 11. The system according to claim 1, wherein the magnetic field changing section includes a magnetic field generating section and a moving section configured to change relative position of the first heat exchange section and the magnetic field generating section.
 12. The system according to claim 1, wherein the magnetic field changing section includes an electromagnet and a switch configured to switch between energization and deenergization of the electromagnet.
 13. The system according to claim 6, further comprising: a piping connecting the first heat exchange section, the second heat exchange section, and the transport section in a closed loop.
 14. The system according to claim 1, wherein the first heat transport medium and the second heat transport medium are separated from each other.
 15. The system according to claim 1, wherein the first heat transport medium and the second heat transport medium are one of gas, liquid, and solid.
 16. The system according to claim 1, wherein the second heat transport medium is air or nitrogen gas.
 17. The system according to claim 1, wherein the first heat transport medium is at least one selected from the group consisting of water, an oil-based medium, and a solvent-based medium.
 18. The system according to claim 13, wherein the transport section circulates the first heat transport medium and the second heat transport medium in a channel formed in a closed loop. 